Staying up whole night to do intensive testing on my A700 + 50mm Vs A700 + Tamron 1750mm Vs A700 + Sal1870....
stars:
TEST NO.1, Shooting Object around 40cm from the camera at 50mm, using F1.4, F2.8, F3.5
Result:
- Sony 50mm is sharpest at
0.5cm - 0.6cm behind focused target.
- Tamron at 50mm is sharpest at
1cm behind focused target
TEST NO.2, Shooting Object around 100cm from the camera at 50mm, using F1.4, F2.8, F3.5
Result:
- Sony 50mm is sharpest at
+- 2cm behind focused target.
- Tamron at 50mm is sharpest at
5cmcm behind focused target
TEST NO.3, Testing Tamron at wide angle 24mm & 17mm at F2.8 & F3.2
Result:
- VERY inconsistent. At 24mm -17mm, backfocusing can be ranging around 1 cm to 2cm... usually d further the subject.. the further d backfocusing..
OTHER TEST: A700 + Kit lens... Very hard to determine... due to kit lens IQ & the F5.6 when zooming at 50-70mm.... but somehow it tells me that is omost the same with the Sony 50mm...
Conclusion: ... no conclusion... Looking at the result & analysis it at the most simple direct way... it could be.. My A700 has BF of 0.5 cm.... Tamron lens oso hv its own BF problem.. of 0.5cm ... therefore 0.5cm A700 + 0.5cm Tamron = 1cm of backfocusing at a distance of around 40cm from distance subject. the BF distance increase as subject further away...
I am about to do operation on my A700 & Tune the focusing myself... not sure is that a death wish... could get worse...